Snowfall may be extremely heavy during some years. For exam- 

 ple, at Tamarack, Alpine County, a total of 884 inches (2,245 

 cm) of snow was recorded during the 1906-07 winter. This is 

 equal to almost 74 feet (22.6 m) of snow! 



Although the temperature regime over much of California is 

 moderate, extreme temperatures have been recorded for various 

 localities. The lowest temperature recorded in the state was 

 -45°F (-43°C) at Boca, Nevada County, which is east of Truckee. 

 This amazingly low temperature was recorded on January 20, 

 1937. Since Boca is only at about 5,500 feet (1 ,676 m) elevation, 

 it is quite probable that even lower temperatures have occurred 

 in the state but have been unrecorded. The highest temperature 

 in the state (and almost the highest temperature for any station 

 on earth) was 134°F (57°C) in Death Valley. Both temperature 

 extremes occurred in areas that are well vegetated, so some plant 

 species are able to tolerate them. 



The frost -free season, which agriculturaUsts call the growing 

 season, varies in length from place to place. The longest growing 

 season is 365 days along parts of the extreme southern coast of 

 California. In the Central Valley the season is about 260 days 

 long. In northeastern California, it is 100 to 120 days long, and 

 at elevations of 6,000 feet (1,829 m) or above it rapidly drops 

 off to below 100 days. There are some areas in the state, there- 

 fore, which rarely if ever experience a frost; other areas in the 

 high montane region may have night-time temperatures that 

 frequently drop to freezing or below even in midsummer. 



The average climate of a region is important in determining 

 what sort of vegetation and plant communities occur there. How- 

 ever, extreme deviations from the average climate may also have 

 a striking effect on the plants of an area and may exert a deter- 

 mining role if these extremes occur frequently. For example, in 

 parts of northern California there was a very hard freeze with 

 unprecedented low temperatures in December, 1972. This ex- 

 terminated or damaged large plantings of orchard crops and 

 ornamentals, and also damaged a number of native trees and 

 shrubs. Similar freezes in the southern part of the Great Basin 

 have been known to kill or damage vast acreages of the native 

 Creosote Bush (Larrea divaricata, Zygophyllaceae) at the north- 



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